1. Field of the Invention
The present invention concerns an artificial water plant system installed on nearshore sea bottom and/or lake bottom, which has an objective of preventing seashores and/or lakeshores from being eroded by wave action by means of a control mechanism of sediment transport which consists of onshore bottom currents induced by wave-water plant interaction and wave energy dissipation by this system.
2. Description of the Prior Art
Rigid structures mainly made of concrete or stone materials such as coastal rivetments, groins, wave absorbing works and detached breakwaters have been constructed or installed so that large offshore waves do not directly reach a seashore. Such rigid structures however, involve an environmental problem of damaging existing ecosystems and worsen the landscape of a seashore. Another problem is that the sea bottom around these rigid structures is scoured by waves breaking and strong bottom currents induced by wave-structure interaction. Subsequently, these structures are subjected to subsidence and collapse.
Submerged breakwaters or artificial reefs have been developed and constructed for landscape conservation and water quality conservation due to a good exchange of sea water. They also, however, involve some problems likely to cause scouring due to waves breaking and strong bottom currents induced by wave-structure interaction and also present navigation hazards for ships.
On the contrary, flexible structures are also provided, such as fibrous or strand-like polymeric materials entangled with each other, nets or swingable rubber sheets. Such flexible structures are preferred in view of their water quality conservation properties since they swing by waves and have sufficient openings for sea water to pass through. In addition they have the advantage of not deteriorating the landscape since the structures are disposed on the sea bottom and do not appear above the water surface.
Since drag forces exerted on those flexible structures increase due to deposition of marine organisms on these structures, they tend to easily fall down due to the weight of deposits such as shells. Also, a screw propeller of a ship may easily catch these structures when the ship goes in the area of the structures, which results in both the ship and the structures being liable to suffer damage. Thus, they involve a drawback of resulting in problems in view of the long-lasting property of the aimed effect and durability. Thus, no effective means for practical use have yet been provided until the present invention.